1. Field of the Invention
The present invention relates generally to user interfaces, and in particular to a minimalist toggle circuit to actuate emitting devices between states.
2. Description of the Related Art
A frequent problem encountered in providing for switches is assuring durability of the switch. Circuit designers often take into account heavy use or exposure to hostile elements, among other things. A common technique designers use is to eliminate mechanical parts in favor of solid state circuit components.
Flashlight manufacturing has undergone a recent shift in technology used. In the 1990s the lowering cost of the light emitting diode, a technology commonly known as LED, made it possible to replace the incandescent bulb with the cooler-running, more durable LED. The shift in the industry is so fundamental that heavy-duty lamps are being retrofitted with LEDs, especially in the traffic signal application area. These LEDs are finding their way into automotive applications and have for many years now, been the preferred method of illuminating cockpits in newly manufactured aircraft.
The massive improvement has led designers to replace the emitting component of flashlights with LEDs. LEDs have a lifetime at least 10 times that of the incandescent bulbs that are replaced. Unfortunately, designers have not yet provided a similarly durable switch, and many flashlights now made have mechanical switches that fail long before the failure of the emitters or even the batteries commonly used to power the flashlight.
Occasionally, users of devices much more complicated than a flashlight may benefit by having a simple code that may enable the device owner to operate the device, but hinder others from using the device. For example, cars may employ a key-code to access a door without use of a conventional key. In addition, mobile devices such as cellular telephones and portable audio devices employ a lock-out mechanism. For those applications that do not require a particularly heavy and complicated code, it would be convenient to have some simplified gesture or user interface to authenticate the user, and reduce part counts to implement such a user interface.
A frequent application of touch circuits is the wall mounted elevator-summoning button. Often designers use such circuits within an elevator itself. Since such circuits seldom fail, the use of the circuit creates a good user experience, since there tends to be a presumption that if the electronics of the elevator work well, then there is a high probability of exiting the elevator unscathed.
Touch circuits are a class of circuit that operates by touching a plate with a substantial conductor, often a limb of the human body. Such circuits even operate if a glove is interposed between a hand and the plate or if the hand approaches extremely proximal to the switch. Extremely proximal means on the order of a millimeter. One type of touch circuit operates because the presence of the human body induces a capacitance on the plate, which changes the circuit in a well-known manner.
Another type of touch circuit detects the presence of a conductor by noting a change in the antenna-like qualities of the plate. Many other types of touch circuits have been used and are well known in the industry. All such circuits have a common feature, a conductive plate.
The touch circuits are well suited to the wall-mount application of an elevator. However, touch circuits, when used on small personal devices, suffer in that users may accidentally actuate the controlled device by the merest touch of their body, or even by contact with pocket change. Some manufacturers supplement their touch user interface with a mechanical switch that must be properly set prior to activation of the conductive plate or plates of the touch circuit controlled user interface. Such mechanical switches add to the cost of the device, and are susceptible to mechanical failure. Moreover, such mechanical switches tend to create additional unsealed openings in a device that tend to make such a device more susceptible to the corrosive effects of moist environments.
Airport runway lighting activates when a transmitter, using standard frequencies, is keyed on in one of several sequences. Such ‘keying on’ is often described as a pilot clicking on the microphone associated with the aircraft transmitter. Three clicks transmitted and received causes the runway controller circuit to set the runway lighting to the lowest level of illumination. The lighting systems only permit turning on the runway lights. To conserve power, the runway lighting systems operate on a timer, such that after an interval, usually 15 minutes, the runway lights are turned off without pilot input. The rationale for permitting only turning on lights is to prevent pranksters from disabling runway lighting by clicking on aviation radios. Particularly in this era of high vigilance concerning aviation, limiting access to airport facilities is a high priority. A downside to this mechanism is that several airports in the same region have the runway lighting system tuned to the same frequencies. Consequently, a pilot within range of two such systems can inadvertently signal a second runway lighting system to turn on. It is unknown for such runway lighting systems to screen out unusually rapid clicking of the microphone. More details are available in the Aeronautical Information Manual, Chapter 2, Section 1 (2-1-7).